This is to stop the loss in the long positions, but there is a saying that the profit occurs when buying and not when selling, so focus on when you buy and not when you sell.
Trailing stops are executed below the support level or the psychological barrier, so that when it is broken, you reach its conviction that the price will not rise again, and therefore it is better to sell. Therefore, it is not placed as a percentage, but rather under the support chart at a rate of 10% to 20%, and not for a specific price, as the support level It varies from one price range to another.

It is easier in Bitcoin and more difficult in altcoin especially pump-and-dump coins, in which technical analysis indicators do not play a main role, and then it is difficult to identify support and resistance points. Therefore, in those currencies you do not do many calculations and consider any gain as a gain because it may not come again.